hange of species, must be termed rapid.
By speculating on such changes, we may easily see how partial waves
of immigration may have entered New Guinea, and how all trace of their
passage may have been obliterated by the subsequent disappearance of the
intervening land.

There is nothing that the study of geology teaches us that is more
certain or more impressive than the extreme instability of the earth's
surface. Everywhere beneath our feet we find proofs that what is land
has been sea, and that where oceans now spread out has once been land;
and that this change from sea to land, and from land to sea, has taken
place, not once or twice only, but again and again, during countless
ages of past time. Now the study of the distribution of animal life upon
the present surface of the earth, causes us to look upon this constant
interchange of land and sea--this making and unmaking of continents,
this elevation and disappearance of islands--as a potent reality, which
has always and everywhere been in progress, and has been the main agent
in determining the manner in which living things are now grouped and
scattered over the earth's surface. And when we continually come upon
such little anomalies of distribution as that just now described, we
find the only rational explanation of them, in those repeated elevations
and depressions which have left their record in mysterious, but still
intelligible characters on the face of organic nature.

The insects of New Guinea are less known than the birds, but they seem
almost equally remarkable for fine forms and brilliant colours. The
magnificent green and yellow Ornithopterae are abundant, and have most
probably spread westward from this point as far as India. Among the
smaller butterflies are several peculiar genera of Nymphalidae and
Lycaenidae, remarkable for their large size, singular markings, or
brilliant coloration. The largest and most beautiful of the clear-winged
moths (Cocytia d'urvillei) is found here, as well as the large and
handsome green moth (Nyctalemon orontes). The beetles furnish us with
many species of large size, and of the most brilliant metallic lustre,
among which the Tmesisternus mirabilis, a longicorn beetle of a golden
green colour; the excessively brilliant rose-chafers, Lomaptera wallacei
and Anacamptorhina fulgida; one of the handsomest of the Buprestidae,
Calodema wallacei; and several fine blue weevils of the genus Eupholus,
are perhaps the most conspicu